Psychopathy is a clinical disorder that is characterised by several interpersonal, affective, and lifestyle characteristics. Despite being recognised as a disorder for hundreds of years, research on psychopathy did not emerge in earnest until approximately forty years ago, spurred by the development and widespread use of psychopathy-specific assessment tools. A well-developed and growing body of empirical research has improved our understanding of psychopathy, including how psychopathy can be measured in clinical contexts, the relationship between psychopathy and certain outcomes that are of interest in the criminal justice system (e.g. risk of recidivism), the use of psychopathy evidence in legal proceedings, and the risk of evaluator bias in the scoring and interpretation of psychopathy measures.